1. Field of the Invention
This invention relates to a liquidometer, and more particularly to an improved liquidometer for continuously measuring small quantities of a sample liquid by integrating flow data obtained from a series of measurements taken in a predetermined period.
2. Description of the Invention
In chemical processing or when measuring a body liquid of a patient in a hospital, it is necessary to successively measure the quantity of a sample liquid having a relatively small flow rate, that is a flow rate of less than 100 cc per minute, with high accuracy and resolution.
For instance, the amount of urine a patient under treatment discharges in a day provides information vital for a doctor to diagnose the condition of the patient accurately. Although such excretions occur in fairly small amounts in a unit period, the gross amount of them when integrated over a period of hours becomes quite large. Accordingly, there has arisen a need for a liquidometer which is capable of accurately effecting a successive recording of the liquid emissions.
Heretofore, a thermal type mass flow meter has been used for successively recording variations in the quantity of excretions with elapsed time. However, a major drawback of such existing apparatus is that the accuracy of the measurement becomes unstable due to changes in flow, or errors occur in the result because the mass or specific heat of the sample, which are used as parameters in the measurement method, can be altered by the presence of other components in the sample liquid.
Further, in the existing flow meter, since a thermal load is applied to the sample liquid, the sample is thermally impaired by a temperature change. Accordingly, such an existing flow meter is not suitable for measuring a chemically treated liquid or body liquid such as urine or the like.